Income Taxes - Establishment of Valuation Allowance (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Decrease in valuation allowance	$ 1.0	$ 77.2

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

Name:	us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration